# include <float.h>
# include <cmath>
# include <cstdlib>

using namespace std;

# include "closest_pair_brute.hpp"

//****************************************************************************80

void closest_pair_brute ( int n, double xy[], double &d, int &i, int &j )

//****************************************************************************80
//
//  Purpose:
//
//    closest_pair_brute() finds closest pair of points in 2d using brute force.
//
//  License:
//
//    This code is distributed under the MIT license.
//
//  Modified:
//
//    03 April 2024
//
//  Author:
//
//    Original MATLAB code by Cleve Moler.
//    This version by John Burkardt.
//
//  Reference:
//
//    Cleve Moler,
//    https://blogs.mathworks.com/cleve/2024/03/28/closest-pair-of-points-problem/
//    Closest pair of points problem,
//    28 March 2024.
//
//  Input:
//
//    int n: the number of points.
//
//    double xy(n,2): the X and Y coordinates of the points.
//
//  Output:
//
//    double &d: the distance of the closest pair.
//
//    int &i, &j: the indices of the closest pair.
//
{
  double d2;
  int i2;
  int j2;

  d = HUGE_VAL;
  i = -1;
  j = -1;

  for ( i2 = 0; i2 < n; i2++ )
  {
    for ( j2 = i2 + 1; j2 < n; j2++ )
    {
      d2 = pow ( xy[i2+0*n] - xy[j2+0*n], 2 )
         + pow ( xy[i2+1*n] - xy[j2+1*n], 2 );
      d2 = sqrt ( d2 );
      if ( d2 < d )
      {
        d = d2;
        i = i2;
        j = j2;
      }
    }
  }

  return;
}